CONTROL OF INDUCTION MOTORS ACADEMIC PRESS SERIES IN ENGINEERING Series Editor J. David Irwin Auburn University This is a series that will include handbooks, textbooks, and professional reference books on cutting-edge areas of engineering. Also included in this series will be single-authored professional books on state-of-the-art techniquesand methodsin engineering.Its objectiveis tomeet theneeds ofacademic,industrial,andgovernmentalengineers,aswellastoprovide instructionalmaterialforteachingatboththeundergraduateandgraduate level. The series editor, J. David Irwin, is one of the best-known engineering educators in the world. Irwin has been chairman of the electrical engi- neering department at Auburn University for 27 years. Published books in the series: Embedded Microcontroller Interfacing for McoR Systems, 2000, G. J. Lipovski Soft Computing & Intelligent Systems, 2000, N. K. Sinha, M. M. Gupta Introduction to Microcontrollers, 1999, G. J. Lipovski Industrial Controls and Manufacturing, 1999, E. Kamen DSP Integrated Circuits, 1999, L. Wanhammar Time Domain Electromagnetics, 1999, S. M. Rao Single-andMulti-Chip MicrocontrollerInterfacing,1999,G. J.Lipovski Control in Robotics and Automation, 1999, B. K. Ghosh, N. Xi, and T. J. Tarn CONTROL OF INDUCTION MOTORS Andrzej M. Trzynadlowski Department of Electrical Engineering University of Nevada, Reno Reno, Nevada San Diego San Francisco New York Boston London Sydney Tokyo This book is printed on acid-free paper. (cid:2)∞ Copyright (cid:3) 2001 by Academic Press All rights reserved. Nopartofthispublicationmaybereproducedortransmittedinanyform orbyanymeans,electronicormechanical,includingphotocopy,recording, or any information storage and retrieval system, without permission in writing from the publisher. Requests for permission to make copies of any part of the work should be mailed to: Permissions Department, Harcourt, Inc., 6277 Sea Harbor Drive, Orlando, Florida, 32887-6777. ACADEMIC PRESS A Harcourt Science and Technology Company 525 B Street, Suite 1900, San Diego, CA 92101-4495, USA http://www.academicpress.com Academic Press Harcourt Place, 32 Jamestown Road, London NW1 7BY, UK Library of Congress Catalog Card Number: 00-104379 International Standard Book Number: 0-12-701510-8 Printed in the United States of America 00 01 02 03 04 QW 9 8 7 6 5 4 3 2 1 To my wife, Dorota, and children, Bart and Nicole Thi s Page Intentionally Lef t Blank CONTENTS Preface xi 1 Background 1 1.1 Induction Motors 1 1.2 Drive Systems with Induction Motors 3 1.3 Common Loads 4 1.4 Operating Quadrants 10 1.5 Scalar and Vector Control Methods 11 1.6 Summary 12 2 Construction and Steady-State Operation of Induction Motors 15 2.1 Construction 15 2.2 Revolving Magnetic Field 17 2.3 Steady-State Equivalent Circuit 24 2.4 Developed Torque 27 vii viii CONTROLOFINDUCTIONMOTORS 2.5 Steady-State Characteristics 31 2.6 Induction Generator 36 2.7 Summary 40 3 Uncontrolled Induction Motor Drives 43 3.1 Uncontrolled Operation of Induction Motors 43 3.2 Assisted Starting 44 3.3 Braking and Reversing 47 3.4 Pole Changing 51 3.5 Abnormal Operating Conditions 52 3.6 Summary 54 4 Power Electronic Converters for Induction Motor Drives 55 4.1 Control of Stator Voltage 55 4.2 Rectifiers 56 4.3 Inverters 64 4.4 Frequency Changers 69 4.5 Control of Voltage Source Inverters 71 4.6 Control of Current Source Inverters 81 4.7 Side Effects of Converter Operation in Adjustable Speed Drives 88 4.8 Summary 91 5 Scalar Control Methods 93 5.1 Two-InductanceEquivalentCircuitsoftheInductionMotor 93 5.2 Open-Loop Scalar Speed Control (Constant Volts/Hertz) 97 5.3 Closed-Loop Scalar Speed Control 101 5.4 Scalar Torque Control 102 5.5 Summary 105 6 Dynamic Model of the Induction Motor 107 6.1 Space Vectors of Motor Variables 107 6.2 Dynamic Equations of the Induction Motor 111 6.3 Revolving Reference Frame 114 6.4 Summary 117 ix CONTENTS 7 Field Orientation 119 7.1 Torque Production and Control in the DC Motor 119 7.2 Principles of Field Orientation 121 7.3 Direct Field Orientation 124 7.4 Indirect Field Orientation 126 7.5 Stator and Airgap Flux Orientation 129 7.6 Drives with Current Source Inverters 134 7.7 Summary 135 8 Direct Torque and Flux Control 137 8.1 Induction Motor Control by Selection of Inverter States 137 8.2 Direct Torque Control 140 8.3 Direct Self-Control 148 8.4 Space-Vector Direct Torque and Flux Control 145 8.5 Summary 157 9 Speed and Position Control 159 9.1 Variables Controlled in Induction Motor Drives 159 9.2 Speed Control 161 9.3 Machine Intelligence Controllers 164 9.4 Position Control 173 9.5 Summary 175 10 Sensorless Drives 177 10.1 Issues in Sensorless Control of Induction Motors 177 10.2 Flux Calculators 179 10.3 Speed Calculators 183 10.4 Parameter Adaptation and Self-Commissioning 191 10.5 Commercial Adjustable Speed Drives 197 10.6 Summary 200 Literature 203 GlossaryofSymbols 221 Index 225